In vitro protein digestibility in grain sorghum: effect of genotype and interaction with starch digestibility

Improvement of nutritive value is one of the main goals of sorghum breeding. It is known that one of the reasons of relatively poor nutritive value of sorghum grain is resistance of its seed storage proteins (kafirins) to protease digestion that also affects digestibility of starch. To study genetic aspects and interdependency of these traits we investigated in vitro protein and starch digestibility of the flour of 12 grain sorghum lines and six F₁ hybrids. Comparison of SDS-PAGE spectra of total grain proteins before and after pepsin digestion revealed that the F₁ hybrids had significantly lower indices of protein digestibility than parental lines, with the exception of the F₁ hybrid M35-1A KB/KVV-45, which retained high level of protein digestibility typical for KVV-45 line. The level of starch digestibility in the F₁ hybrids corresponded to its level in maternal lines suggesting importance of maternal genotype in determination of this trait. It was found that starch digestion by amylolytic enzymes increased the amount of protein in individual kafirin fractions, and reduced the amount of high molecular weight proteins as well it reduced subsequent kafirin digestion by pepsin and caused formation of polypeptide (M_r ~45 kDa), perhaps, the kafirin dimer, resistant to pepsin digestion. These data are of importance for fundamental investigation of factors influencing kafirins and starch interactions in sorghum endosperm and their digestibility.     

Expression of resistance to Atherigona soccata in F1 hybrids involving shoot fly-resistant and susceptible cytoplasmic male-sterile and restorer lines of sorghum

In recent years, cytoplasmic male‐sterility (CMS) has been recognized as a potential danger to the stability of crop production and resistance to insect pests in sorghum. Therefore, the influence of CMS on the expression of resistance to sorghum shoot fly was studied at the ICRISAT, Patancheru, India using the interlard fishmeal technique. The experimental material consisted of 12 restorer, 12 CMS and the maintainer lines, and their 144 F₁ hybrids. Shoot fly‐resistant CMS lines were preferred for oviposition and had more damage because of deadhearts than the corresponding maintainer lines. The hybrids based on shoot fly‐resistant CMS × resistant restorer lines were significantly less preferred for oviposition than the hybrids based on other cross combinations and exhibited the highest frequency (69.1%) of shoot fly‐resistant hybrids. The hybrids based on glossy and trichomed parents had the highest frequency (>90%) of hybrids with glossy and trichome traits, emphasizing the need to transfer these traits into both parents for better expression in the F₁ hybrids. The expression pattern of trichome density, leaf glossiness and leaf sheath pigmentation in the F₁ hybrids and their parents suggested that the interactions between cytoplasmic and nuclear genes possibly control the expression of traits associated with resistance to sorghum shoot fly in the F₁ hybrids.     

Identification of stable restorers and genetics of fertility restoration in late‐maturing pigeonpea [Cajanus cajan (L.) Millspaugh]

A total of sixty‐six germplasm lines were crossed with five CMS lines, where two belong to A₄ cytoplasm, while other three belong to A₂ cytoplasm. On the basis of pollen fertility test as well as good pod setting, of 330 hybrids, 34 restorer lines were observed in ICPA 2043 and 19 in ICPA 2092. Thirteen germplasm lines restored fertility in both the A₄ CMS lines, viz. ICPA 2043 and ICPA 2092; however, none of the lines restored fertility in A₂ CMS lines. For confirmation of result, restoration competence of identified lines tested subsequently 2 years at two different temperatures. The segregation patterns for fertility restoration studied in F₂ and BC₁F₁ generations of selected ten crosses. Six crosses indicated the involvement of two major genes with recessive epistasis, three crosses confirmed dominant epistasis, and one cross indicated the involvement of duplicate recessive epistasis. The obtained results from this study will hasten the future three‐line breeding programme and lead the hybrid technology to the farmers' field with the better exploitation of CMS lines.     

Diversity among sources of cytoplasmic male sterility in sunflower (Helianthus annuus L.)

Summary Ten cytoplasmic male sterile (CMS) sunflower (Helianthus annuus L.) lines were crossed with nine maintainer or male fertility restorer lines in a diallel crossing scheme. Based on fertility restoration of the F₁ generation, CMS lines were divided into four groups. At least two new sources of CMS, CMS PET2 and CMS GIG1, were found to be potentially useful for commercial production of hybrids. Environment had an influence on fertility restoration of one CMS line, CMS MAX1. Effective restoration of male fertility for CMS RIG1, CMS ANN2, and CMS ANN3 was not found.     

A unique introgression from Moricandia arvensis confers male fertility upon two different cytoplasmic male-sterile lines of Brassica juncea

A Brassica juncea line carrying an introgression from Moricandia arvensis restored male fertility to two cytoplasmic male‐sterile (CMS) B. juncea lines carrying either M. arvensis or Diplotaxis catholica cytoplasm. Genetics of fertility restoration was studied in the F₁, F₂, F₃ and backcross generations of the cross between CMS and fertility‐restorer lines. No male‐sterile plants were found in F1‐F₃ generations of the cross between CMS [M. arvensis] B. juncea and the restorer. However, a 1: 1 segregation for male sterility and fertility was observed when the F1 was pollinated with non‐restorer pollen from a euplasmic line. These results clearly show that restoration is mono‐genic and gametophytic. In CMS lines carrying D. catholica cytoplasm, the restorer conferred male fertility to the F1 and showed 3: 1 and 1: 1 segregations for male fertility and sterility in F₂ and BC1 generations, respectively, indicating a monogenic, sporophytic mode of fertility restoration. The results were also supported by pollen stainability in the F1 which was about 65% in M. arvensis‐based CMS and >90% in D. catholica‐based CMS. The above results are discussed in the light of previous molecular studies which showed association between CMS and atpA in both systems.     

Genetic Divergence and Molecular Characterization of Sorghum Hybrids and their Parents for Reaction to Atherigona Soccata (Rondani)

Summary Simple sequence repeat (SSR) markers linked to quantitative trait loci (QTL) associated with resistance to sorghum shoot fly, Atherigona soccata resistance were used to characterize the genetic and phenotypic diversity of 12 cytoplasmic male-sterile (CMS) and maintainers, 12 restorer lines, and 144 F₁ hybrids. The genetic diversity was quite high among the shoot fly-susceptible parents and the hybrids based on them, as indicated by high polymorphic information content (PIC) values, while limited genetic diversity was observed among shoot fly-resistant lines. The phenotypic and genotypic dissimilarity analysis indicated that the shoot fly-resistant and -susceptible parents were 73.2 and 38.5% distinct from each other, and the morphological and genetic distances of certain resistant and susceptible cross combinations was more than their resistant or susceptible parents. Genetic variability among the groups was low (10.8%), but high within groups (89.2%). The genetic and morphological distances suggested that the F₁ hybrids were closer to CMS (5 to 12% dissimilar) than the restorer (11 to 87% dissimilar), suggesting that CMS influences the expression of resistance to sorghum shoot fly. The SSR markers can be used to characterize the homologous traits in sorghum germplasm.     

Interspecific cross‐hybrids of Nicotiana tabacum L. cv. (gla.) S ‘K326’ with Nicotiana alata

In order to introduce the Tomato Spotted Wilt Virus (TSWV) resistance from Nicotiana alata into Nicotiana tabacum, a cytoplasmic male sterility (CMS) line of N. tabacum (N. tabacum L. cv. (gla.) S ‘K326’), was successfully crossed with N. alata. Despite a high DNA content variability, F₁ hybrids could be classified in two subgroups, a major one encompassing fertile hybrids morphologically similar to their tobacco maternal parent but TSWV sensitive, and a minor one displaying sterile hybrids showing an intermediate phenotype and TSWV resistant. In order to elucidate the unexpected fertility recovery of the fertile F₁ plants, some N. alata fertility restoration ppr genes were cloned and were shown to be differentially expressed between parental lineages as well as between both F₁ subgroups, suggesting that N. alata contains fertility restoring allele able to overcome the CMS of N. tabacum.     

Breeding of widely compatible restorer lines in rice (Oryza sativa L.) through anther culture

Following anther culture of various F₁ hybrids of indica restorer (R) lines/wide compatible varieties (WCVs) and japonica R lines/WCVs, the homozygous diploid plants (2n) generated were test-crossed with indica WA type cytoplasmic-genetic male sterile (CMS) line Zhanshan 97A (WA), indica testers Nanjing 11 and Nante, japonica BT CMS line Hanfeng A (BT), and japonica testers Balilla and Akihikari to identify widely compatible restorer lines. The results of this study showed that among the diploid pollen plants generated from F₁ hybrids of indica R lines/WCVs, 36.7% and 64.7% possessed normal fertility restoration ability (rate of seed-setting > 80%) to Hanfeng A and Zhanshan 97A, respectively. 71.3% and 32.3% had normal fertility restoration ability to Hanfeng A and Zhanshan 97A, respectively, in diploid pollen plants derived from the japonica R lines/WCVs F₁'s anther culture. Several widely compatible R lines were selected from anther culture of F₁ hybrids of indica R lines/WCVs and japonica R lines/WCVs. These widely compatible R lines derived from diploid pollen plants showed good wide compatibility and restoration ability both to WA and BT type CMS lines. Strong standard heterosis of major agronomic traits and yield traits was observed in F₁ test-crosses of widely compatible R lines with Hanfeng A and Zhanshan 97A. The wide compatibility in widely compatible R lines H17, H158 and H281 was studied by a set of three-way crosses. Segregation of the fertile plants with seed-setting rate > 70% and semi-fertile plants with seed-setting rate > 69.9% agreed with a ratio of 1:1, indicating that wide compatibility in these widely compatible R lines is governed by a pair of major genes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Interspecific amphiploid‐derived alloplasmic male sterility with defective anthers,narrow disc florets and small ray flowers in sunflower

The cytoplasmic male‐sterility (CMS)/fertility‐restoration system is important for hybrid sunflower (Helianthus annuus L.) seed production. The objective of this study was to characterize two novel alloplasmic CMSs, designated CMS GRO1 and CMS MAX3, with defective anthers, narrow disc florets with no swollen corolla, and short, narrow ray flowers derived from two tetraploid amphiploids (AMPs). Among 26 tested lines, only AMP Helianthus cusickii/P 21 and HA 410 failed to restore male‐fertility. Segregation of CMS, male‐fertile plants and plants with reduced male‐fertility was observed both in the testcross progeny of a six line half‐diallel cross of F₁s with CMS MAX3 and in an F₂ population of CMS GRO1 × RHA 274. Male‐fertility restoration was controlled by at least two dominant genes. Detailed analysis of the mitochondrial genes may provide insight into the differences between these CMSs and other CMS lines. The new CMSs will facilitate the studies of the incompatibility between cytoplasmic and nuclear genes, especially for the alloplasmic CMS involving perennial species, and also provide unique ornamental flower types and CMS sources for hybrid sunflower breeding.     

Relative susceptibility of different male-sterile cytoplasms in sorghum to shoot fly, <Emphasis Type="Italic">Atherigona soccata</Emphasis>

Summary The shoot fly, Atherigona soccata is an important pest of sorghum, and host plant resistance is one of the most effective components for managing this pest. Most of the hybrids grown in India based on milo cytoplasm (A₁ cytoplasm) are highly susceptible to shoot fly. Therefore, the present studies were undertaken to evaluate different male-sterile cytoplasms (CMS) for their relative susceptibility to sorghum shoot fly. Oviposition and deadheart formation were significantly lower on the maintainer lines as compared to the corresponding male-sterile lines. Among the cytoplasms tested, A₄M cytoplasm showed antixenosis for oviposition and suffered lower deadheart formation than the other cytoplasms tested. The A₄G₁ and A₄M cytoplasms suffered lower deadhearts in tillers than the other cytoplasms. Recovery following shoot fly damage in A₄M, A₃, and A₂ cytoplasms was better than in the other cytoplasms tested. The larval and pupal periods were longer and male and female pupal weights lower in A₄M and A₄VzM CMS backgrounds compared to the other CMS systems. Fecundity and antibiosis indices on CMS lines were lower than on the B-lines. The A₄M cytoplasm was found to be relatively resistant to sorghum shoot fly, and can be exploited for developing shoot fly-resistant hybrids for sustainable crop production in future.     

Moricandia arvensis cytoplasm based system of cytoplasmic male sterility in Brassica juncea: Reappraisal of fertility restoration and agronomic potential

Cytoplasmic male sterility (CMS) system based on the cytoplasm from Moricandia arvensis (mori) was investigated for fertility restoration and agronomic potential. Fertility restorer gene for mori CMS was introgressed from cytoplasm donor species as all the evaluated Brassica juncea genotypes (155) acted as sterility maintainers. The allosyndetic pairing between M^a and the A/B genome chromosomes in the monosomic addition plants (2n= 18II + 1M^a) facilitated the gene introgression. Partial fertility restoration (43–52% pollen grain stainability) in F₁ hybrids and absence of segregation for male sterility in F₂ progenies suggested gametophytic control of fertility restoration. The pollen fertility in the F₁ hybrids was, however, sufficient to ensure complete seed set upon bag selfing. Introgression from M. arvensis also helped in correction of chlorosis associated with mori cytoplasm in CMS and fertile alloplasmic B. juncea plants. Yield evaluation of thirty F₁ hybrids having the same nuclear genotype but varied male sterilizing cytoplasms (mori, oxy, lyr, refined ogu), in comparison to respective euplasmic hand bred control hybrids, allowed an estimate of yield penalty associated with different CMS systems. It ranged from 1.8% to 61.6%. Hybrids based on cytoplasmically refined ogu were most productive followed by those based on cytoplasmically refined mori CMS. The male sterility systems emanating from somatic hybridization were found superior than those developed from sexual hybridization.     

Cytoplasmic male sterile and doubled haploid lines with desirable combining ability enhances the concentration of important antioxidant attributes in <Emphasis Type="Italic">Brassica oleracea</Emphasis>

The Brassica vegetable crops are rich source of important antioxidant compounds having anticancer and health promoting properties. Development of F₁ hybrids with better nutritional traits is one of the main breeding objectives in different vegetable crops. Our study is the first report of determining heterotic combinations utilizing cytoplasmic male sterile (CMS) and doubled haploid (DH) inbred lines for antioxidant compounds in snowball cauliflower. Twenty genetically diverse Ogura CMS lines of cauliflower and six DH male fertile inbred lines were crossed to develop 120 F₁ hybrids in line?×?tester mating design. The resulting 120 test cross progenies along with 26 parents and 4 standard checks were evaluated in 10?×?15 alpha lattice design with three replications during next cropping season. The CMS lines Ogu33-1A, Ogu122-5A and Ogu119-1A were good general combiner and CMS line Ogu118-6A was poor general combiner for majority of traits. Most of the heterotic hybrids were associated with high positive SCA effects. The proportions of σ²A/D and \(\upsigma^{2}_{\text{gca}} /\upsigma^{2}_{\text{sca}}\) ratios were less than unity in all the cases indicating preponderance of non-additive gene action in the genetic control of all the traits. Highest number of heterotic hybrids with SCA effects in desired positive direction was recorded for ascorbic acid content and phenolic content followed by total carotenoid content. The F₁ hybrids with better combining ability and better per se performance could be useful in accumulation of favourable allele for higher concentration of important anti-oxidant compounds.     

大豆质核互作雄性不育系NJCMS3A双亲雄性育性基因的SSR标记

利用大豆质核互作雄性不育系NJMCS3A的质、核供体亲本N21566和N21249构建F₂和BC₁F₁育性分离群体进行雄性育性的遗传分析与基因定位。结果表明, F₁正反交可育,F₂和BC₁F₁的可育株与不育株分离比例经χ²测验分别符合3∶1和1∶1,表明NJCMS3A供体亲本雄性育性由一对基因控制,可育等位基因为显性。该基因可能是NJCMS3A的一个恢复基因。选用793对SSR引物对F₂和BC₁F₁群体分别进行育性基因定位,发现该育性基因位于O连锁群上,在Satt331和Satt477标记之间,与Satt331、CSSR133和Satt477标记距离的次序一致,分别为8.1~10.4 cM、11.4~16.4 cM、13.3~19.2 cM。     

Influence of water availability on fertility restoration of CMS lines with the 'M35', A4 and '9E' CMS-inducing cytoplasms of sorghum

Male fertility restoration in new types of sorghum cytoplasmic male sterility‐inducing cytoplasms (A4, ‘9E’, ‘M35’), characterized by the formation of non‐dehiscent anthers, is difficult. Lines with fertility‐restorer genes for these unique cytoplasms do occur, but rarely, and when found tend to be unstable in their inheritance and expression. The aim of this research was to explore reasons for this instability. Seven lines in three unique cytoplasms, ‘9E’, A4 and ‘M35’, and six lines that restore with these cytoplasms were grown at the Agricultural Research Institute for South‐East Region in Saratov, Russia from 1993 to 2004. Levels of male fertility restoration and various environmental factors were recorded. It is reported that for sorghum hybrids in the A4, ‘9E’ and ‘M35’ male‐sterile cytoplasms, the level of plant male fertility is determined by the level of water available to plants during anther and pollen formation that which ‘switches on’ the expression of fertility‐restoring genes, and is possibly involved in an unusual type of male fertility inheritance in these cytoplasms. The creation of reliable line‐fertility restorers capable of the restoration of male fertility of F₁ hybrids in ‘M35’ cytoplasm under conditions of water stress is also reported. Current research explore mechanisms involved possible in responses to water levels at various growth stages and their influence on fertility within these cytoplasms.     

Inheritance and chromosome location of photoperiod‐thermo sensitive male sterility in wheat line Xinong 291S

The present research aimed to study the inheritance and chromosomal location of a photoperiod‐thermo sensitive male sterility (PTSMS) gene in Xinong 291S (XN291S), which is a new PTSMS wheat line. The inheritance was studied in F₁ and F₂ populations derived from crosses between XN291S and eight wheat cultivars. All F₁ plants were fertile and the F₂ populations segregated in either 15 : 1 or 3 : 1 fertile : sterile ratios indicating that PTSMS was controlled by one or two recessive major genes. Five wheat cultivars carried homozygous dominant alleles for fertility, whereas the other three, including ‘Chinese Spring’ (CS), carried a single homozygous dominant allele. Chromosomal location of the PTSMS gene was studied by crossing a set of CS nulli‐tetrasomic lines to XN291S. Self‐fertility of F₁ hybrids XN291S/N5BT5A and XN291S/N5BT5D were significantly lower than the others. Therefore, the PTSMS gene in XN291S that differed from CS was located on chromosome 5B. Location of the second PTSMS gene needs further study.     

Use of androgenesis in intersubspecific hybrid rice breeding

Significant differences of callus induction, green plant regeneration and culture efficiency were observed among restorer lines and their hybrids in rice. Average callus induction percentage of F₁, hybrids was about twice that of their parents. Twenty doubled haploid (DH) lines that showed normal fertility with both indica and japonica CMS lines, were selected as widely compatible restorers (WCRs). TG8 derived from CPSLO17/Minghui 63 not only showed normal fertility to both indica and japonica test varieties and CMS lines, but also exhibited superior agronomic traits, in particular short plant, desired plant type, high tillerability, large panicles, good grain quality and resistance to rice blast disease. Strong heterosis for yield was observed in crosses between indica or japonica CMS lines and TG8. TG8 possessed a dominant, widely compatible gene (WCG) that was inherited from the variety CPSLO17. Results confirmed that the anther culture technique is a quick and effective way of developing widely compatible restorers in rice and that it is applicable to the direct use of intersubspecific heterosis with the three-line method.     

Molecular detection of WA‐CMS restorers from tropical japonica‐derived lines,their evaluation for fertility restoration and adaptation

Hybrid rice based on wild‐abortive cytoplasmic male sterility (WA‐CMS) is important in boosting rice production, which requires diverse parents to harness heterosis. For this, exploiting the diversity of japonica through tropical japonica (TRJ) lines is an excellent route. In this study, 310 TRJ‐based new plant type (NPT) lines were developed and evaluated for Rf3 and Rf4 genes. Gene‐based (DRRM‐Rf3‐5 and DRRM‐Rf3‐10) and functional marker (RMS‐SF21‐5) targeted Rf3 locus, while gene‐linked (RM6100) and functional marker (RMS‐PPR9‐1) targeted the Rf4 locus. The frequency of the restorer allele of Rf3 gene was lower when compared to that of Rf4. Combined phenotypic and molecular screening using gene‐based and functional markers identified 42 lines that carried Rf3 and/or Rf4 genes. All the selected lines produced fertile F₁s when crossed to a WA‐CMS line, “Pusa 6A”, but with varying levels of spikelet fertility. This is the first report of a marker‐cum‐phenotype‐based restorer selection using TRJ‐derived lines. Multilocation evaluation of these lines at three locations indicated better adaptation for grain yield in some of the lines.     

Apomictic frequency in sorghum R473

Summary Apomixis has been reported in a few lines of sorghum, among them R473 which was originally reported to be an obligate apomict. Although this line has multiple embryo sacs, the frequency of apomictic seed formation has not been determined because a progeny test has not been possible. R473 does not cross as a female with other lines except when its own pollen is present. In the present study mutations were induced in R473 by hydrazine and irradiation. Crosses were made between male-sterile mutants as females and normal R473 as males. Plants of R473 produced F₁ hybrids sexually, thus indicating that they were not obligate apomicts. These F₁'s also reproduced sexually, as indicated by segregation for male sterility and male fertility in F₂ progenies.     

Development of cytoplasmic-genic male sterility in safflower

An interspecific cross was made between Carthamaus oxyacantha and the cultivated species C. tinctorius to develop a cytoplasmic‐genic male sterility (CMS) system in safflower. C. oxyacantha was the donor of sterile cytoplasm. The 3: 1 segregation pattern observed in BC₁F₂ suggested single gene control with dominance of male‐fertility over male‐sterility. The information obtained from crossing male sterile X male fertile plants in BC₁F₃ and BC₁F₄ generations showed statistically significant single gene (1: 1) segregation for male sterility vs. male fertility. The results demonstrated that C. tinctorius possesses a nuclear fertility restorer gene and that a single dominant allele restored fertility (Rf) in progeny carrying CMS cytoplasm of C. oxyacantha. Male sterility occurred with the homozygous recessive condition (rfrf) in a sterile C. oxyacantha cytoplasm background and not in the normal cytoplasm of C. tinctorius. The genetic background of different restorer lines of C. tinctorius having normal cytoplasm did not effect fertility restoration. The absence of male sterile plants in C. tinctorius populations ruled out the possibility of genetic male sterility. Normal meiosis in F₁ and BC₁F₂ ruled out a cytogenetic basis for the occurrence of male sterility.     

Conversion of the genic male sterility (GMS) system of bell pepper (Capsicum annuum L.) to cytoplasmic male sterility (CMS)

Non‐pungent bell pepper (Capsicum annuum L.) lacks the cytoplasmic male sterility (CMS) nuclear restorer allele, Rf, and CMS cannot be employed in its F₁ hybrid seed production. To demonstrate that the genic male sterility (GMS) system in non‐pungent bell pepper can be converted to the CMS male sterility system, the conversion of GMS to CMS for non‐pungent bell pepper line GC3 was conducted by introgression of S‐type cytoplasm and the Rf allele from tropical pungent donors. After morphological traits were evaluated, two lines from BC₁F₁ containing S‐type cytoplasm and four lines from BC₂F₂ containing Rf allele, phenotypically similar to GC3, were obtained and could be employed as CMS male sterile lines and restorer lines for non‐pungent bell pepper. Four molecular markers potentially linked to traits of interest were also evaluated in BC₁F₁ and BC₁F₂ populations. This is the first time that GMS has been successfully converted to CMS in bell pepper, a significant contribution for bell pepper hybrid seed production.