Molecular mapping of a locus controlling resistance to Albugo candida in Indian mustard

Brassica juncea (L.) Czern & Coss is widely grown as an oilseed crop in the Indian subcontinent. White rust disease caused by Albugo candida (Pers.) Kuntze is a serious disease of this crop causing considerable yield loss every year. The present study was undertaken to identify molecular markers for the locus controlling white rust resistance in a mustard accession, BEC‐144, using a set of 94 recombinant inbred lines (RILs). The screening of individual RILs using an isolate highly virulent on the popular Indian cultivar ‘Varuna’ revealed the presence of a major locus for rust resistance in BEC‐144. Based on screening of 186 decamer primers employing bulked segregant analysis (BSA), 11 random amplified polymorphic DNA markers were identified, which distinguished the parental lines and the bulks. Five of these markers showed linkage with the rust resistance locus. Two markers, OPN0_l000 and OPB06₁₀₀₀, were linked in coupling and repulsion phases at 9.9 cM and 5.5 cM, respectively, on either side of the locus. The presence of only two double recombinants in a population of 94 RILs suggested that the simultaneous use of both markers would ensure efficient transfer of the target gene in mustard breeding programmes.     

SCAR marker tagged to the alien leaf rust resistance gene Lr19 uniquely marking the Agropyron elongatum-derived gene Lr24 in wheat: a revision

A sequence characterized amplified region (SCAR) marker tagged to an Agropyron elongatum‐derived leaf rust resistance (Lr) gene Lr19 was validated on 18 known alien Lr gener in near‐isogenic lines (NILs) in the variety ‘Thatcher’, along with three wheat cultivers carrying Lr24 and two carrying Lr19. The marker was expressed only in the Lr24 lines confirming that the marker tagged the geneLr24. The monomorphic expression of the SCAR marker in 10NIL pairs for Lr19 and Lr24 revealed that each NIL pair possessed the same gene, Lr24. The donor parents used in the NIL pairs for Lr19 (‘Sunstar*6/C80‐1′) and Lr24 (‘TR380‐14*7/3Ag#14′) amplified the same fragment. Nonsegregation for leaf rust in the F₂ population of the cross between the above donor parents confirmed the presence of the same gene in the two parents. Apparently, a genuine parent stock of ‘Sunstar*6/C80‐1’ was not involved in the development of the NIL pairs for Lr19 due to an improper maintence bredding protocol either at source or destination which went undetected in the absence of signs of virulence for either gene in the region.     

Race-specific aspects of partial resistance in wheat to wheat leaf rust,Puccinia recondita f.sp. tritici

Summary Partial resistance (PR) in wheat to wheat leaf rust (Puccinia recondita f.sp. tritici) is characterized by a slow epidemic build-up despite a susceptible infection type. Two greenhouse tests and two field tests, in which 11 spring wheat cultivars were exposed to five wheat leaf rust races, revealed some indication for race-specificity of PR.In the greenhouse, the expression of PR was highly dependent on the environment. Significant cultivar-race interactions in the first experiment were lost in the second experiment probably due to cultivar-environment and cultivar-race-environment interactions.In the polycyclic field tests several factors played a role in explaining the inconsistency of the cultivar-race interactions, such as differences in initial inoculum, genotypic differences in earliness, interplot interference or environmental conditions.One cultivar-race combination showed a significant but small interaction towards susceptibility in both field experiments. The interaction was probably too small to detect in the monocyclic greenhouse tests. The results do not conflict with the idea that a gene-for-gene relationship could exist between PR-genes in the host and genes in the pathogen.Some problems with regard to the selection of PR in wheat to wheat leaf rust are discussed.     

Interplot interference and the assessment of barley cultivars for partial resistance to leaf rust,Puccinia hordei

Summary The barley cultivars Akka, highly susceptible, and Vada, partially resistant to barley leaf rust, Puccinia hordei, were evaluated for the amount of leaf rust in five experimental field plot situations over three successive years. The field plot situations were: A) plots well isolated from each other by distance and non-leaf rust contributing host plants; B) adjacent plots of 4×41/2 m (18 rows); C) adjacent plots of 4×11/2 m (6 rows); D) adjacent plots of 4×1/4 m (1 row); E) adjacent plots of only one plant (cultivar mixtures).The sporulating leaf area of each plot was measured from samples of 20 tillers taken at random from each plot. In each year the difference in sporulating area between Akka and Vada was large to very large in the absence of interplot interference in the isolated plots, ranging from 150 to 2100 times. In the adjacent plots the partial resistance of Vada was greatly underestimated, 5 to 16 times in the situation B, 14 to 30 times in C, and 75 to 130 times in D and E.Testing lines or cultivars in adjacent plots is the standard procedure in use in breeding programs and in tests of cultivars for their agricultural value. To avoid such under estimation the following procedure is suggested. A few cultivars representing the known range of partial resistance and whose level of partial resistance is well known are evaluated together with the lines and cultivars whose partial resistance has to be assessed. This is demonstrated with a number of cultivars of which resistance values are know from the recommended variety lists for England and Wales. Cultivars have been assessed in Wageningen over four years together with the check cultivars Akka, Sultan, Julia and Vada representing the range of partial resistance with values (on a 1 to 10 scale) of 1, 3–4, 7 and 8 respectively, based on isolated plots experiments.     

Further evidence of polygenic inheritance of partial resistance in barley to leaf rust,Puccinia hordei

Summary The latent period (LP) is a crucial component of partial resistance. Five cultivars, L94, Sultan (Su), Volla (Vl), Julia (Ju) and Vada (Va), representing the known range in partial resistance and LP were crossed in a diallel, and the F₁, F₂ and F₃ tested. The LP effectuated by the five cultivars is about 9, 10^1/2, 10^1/2, 13 and 15^1/2 days, respectively. The crosses Su×L94, Vl×L94 and Ju×L94 had an F₂ positively skewed. Their F₂ means were similar or only slightly larger than the F₁ means. The F₂ frequency distributions in the crosses Vl×Su, Ju×Su and Ju×Vl were normal or nearly so with F₁ and F₂ means similar to each other and to the mid-parent value. The crosses involving Va as a parent again showed a positive skewness but with F₂ means considerably larger than the F₁ moans.Most F₂'s ranged from the low parent to the high parent values without transgression. In the crosses Va×L94 (reported earlier) and Ju×L94 the parental values were not recovered among 216 and 154 F₂ plants, respectively. The cross Ju×Va showed transgression beyond the low parent, Ju.From these data it is concluded, assuming no linkage, that seven loci are involved. The + alleles (governing a longer LP) are thought to be distributed over the parents as follows: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaqGmb% GaaeyoaiaabsdacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaab2cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiai% aabccacaqGGaGaaeiiaiaabccacaqGTaGaaeylaiaabccacaqGGaGa% aeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeylaiaab2caca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaa% b2cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaae% iiaiaabccacaqGTaGaaeylaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeiiaiaabccacaqGGaGaaeylaiaab2cacaqGGaGaaeiiaiaabc% cacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGTaGaaeyl% aiaabccaaeaacaqGtbGaaeyDaiaabccacaqGGaGaaeiiaiaabccaca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaa% bccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae% 4kaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqG% RaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaab2% cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeii% aiaabccacaqGTaGaaeylaiaabccacaqGGaGaaeiiaiaabccacaqGGa% GaaeiiaiaabccacaqGGaGaaeylaiaab2cacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGTaGaaeylaa% qaaiaabAfacaqGSbGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqGRaGaaeiiaiaabc% cacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqGRaGaaeii% aiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeylaiaab2cacaqGGa% GaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUca% caqGRaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiai% aab2cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGa% aeiiaiaabccacaqGTaGaaeylaiaabccacaqGGaGaaeiiaiaabccaca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaab2cacaqGTaaabaGaaeOs% aiaabwhacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGa% GaaeiiaiaabccacaqGGaGaae4kaiaabUcacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaabccacaqGGaGaae4kaiaabUcacaqGGaGaaeiiai% aabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaabccacaqGGaGa% aeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaabccaca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaa% bccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaab2cacaqGTaGaae% iiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeylaiaab2caaeaacaqGwbGaaeyyaiaabccacaqGGaGaaeiiai% aabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqGRaGa% aeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcaca% qGRaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaae4kaiaa% bUcacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaae% 4kaiaabUcacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeylaiaab2cacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabc% cacaqGGaGaae4kaiaabUcacaqGGaGaaeiiaiaabccacaqGGaGaaeii% aiaabccacaqGGaGaaeiiaiaabUcacaqGRaaaaaa!1BBA!\[\begin{gathered} {\text{L94 - - - - - - - - - - - - - - }} \hfill \\ {\text{Su + + + + + + - - - - - - - - }} \hfill \\ {\text{Vl + + + + - - + + - - - - - - }} \hfill \\ {\text{Ju + + + + + + + + + + - - - - }} \hfill \\ {\text{Va + + + + + + + + - - + + + + }} \hfill \\ \end{gathered} \]The genes are supposed to act additively (intermediate inheritance) with the exception of one locus (the 6th or 7th locus) which shows dominance for the shorter LP (for the-alleles). The effect of this locus on LP seems considerably larger than that of the other loci. There are indications of physiological barriers, which means that LP's shorter than the one of L94 or much longer than that of Va are not possible.The effect of + genes in genotypes governing LP's close to these barriers (with very few or very many + alleles respectively) is smaller than in genotypes governing intermediate LP's.     

一种新的竞争指标——树冠影响度

可变竞争区域类竞争指标根据对象木某个描述型指标函数确定竞争区域;而树冠在树木的生长过程中具有重要的作用,并且反映了树木的长期竞争水平,根据这两种思想提出一种新的竞争可变区域类竞争指标——树冠影响度。采用典型选样法设置研究样地,并对样地内树种的各个测树因子进行调查统计,应用树冠影响度对数据进行分析讨论,结果显示:样地树种平均树冠影响度为0.359 4,样地中群落竞争相对较弱,群落结构相对稳定,其中马尾松(Pinus massoniana)的树冠影响度最小,为0.261 3;枫香(Liquidambar formosana)的树冠影响度最大,为0.510 1。优势种群树种平均树冠影响度小于非优势种群树种,优势种群受到的竞争较小,竞争能力较强,针叶树种平均树冠影响度小于阔叶树种树种,针叶树在群落中处于优势地位。     

Vegetative Growth,Yield and Leaf Mineral Composition in Strawberry (Fragaria × Ananassa DUCH. CV. Pajaro) as Influenced using Nickel Sulfate and Urea Sprays

In this study, interactions of nickel sulfate and urea sprays on vegetative growth, yield and leaf mineral contents in strawberry were investigated. Rooted Pajaro strawberry plants were potted in 3 liter pots filled with soil, leaf mold and sand (1:1:1, v/v/v). Established plants were foliar sprayed with nickel sulfate at 0, 150, 300 and 450 mg L^?1 and urea 0 and 2 g L^?1 concentrations. Results indicated that nickel (Ni; 300 mg L^?1) plus urea (2 g L^?1) significantly increased the yield and runner numbers. Nickel sulfate at the rate of 300 and 150 mg L^?1and urea (2 g L^?1) significantly increased the crown numbers. The greatest root fresh and dry weights were obtained from untreated plants. Urea at 2 g L^?1 without nickel significantly increased shoot fresh and dry weights. Nickel at 450 mg L^?1 without urea significantly increased Ni concentration in leaves. Overall, nickel sulfate at 150 and 300 mg L^?1 along with urea at 2 g L^?1 were the best treatments.     

14个小麦品种(系)抗叶锈性分析

选用16个小麦叶锈菌菌系对14个小麦品种(系)进行抗叶锈性鉴定和苗期抗叶锈基因推导,初步分析这些品种(系)的抗性和携带的抗病基因;进一步利用21个与Lr基因紧密连锁或共分离的分子标记,对这14个品种(系)中可能含的抗叶锈基因进行鉴定。结果表明,s98351-2-2-2-1可能含Lr3a、Lr28和Lr50;9629-03A-4-1-1可能含Lr37;97167-1-2-1-1-2-1、919-20-2c2、9589、免中438、9916-8-6和9916-8-18含Lr26;96104-1-5-1c2可能含Lr28;00-55-3-1-1含Lr1;1R13可能含Lr24、Lr37和Lr38;1R17可能含Lr24和Lr38;1R35含Lr10和Lr34,还可能含Lr3a和Lr50;9524-1-2-2-1含未知抗叶锈基因或本试验使用的已知抗病基因以外的抗叶锈基因。所有品种(系)均不含Lr9、Lr19、Lr20、Lr21、Lr29、Lr35、Lr42和Lr47基因。测试的14个品种(系)中有比较丰富的抗叶锈病基因,可为育种提供丰富的抗源。     

甘蔗对锈病的抗性遗传与育种策略──Ⅰ．F_1群体对锈病抗性的分析

以甘蔗２０个杂交组合的实生苗为试验材料,在田间自然诱发条件下,按０－９级抗感分级标准分析了甘蔗Ｆ１群体对锈病的抗性．结果表明：２０个家系实生苗对锈病抗性分离较大,普遍呈现偏向抗锈级别的偏态分布．根据χ２测验所显示的４种抗锈频次分布型,提出了选择抗锈单株的相应策略．从后代群体的抗病表现评价亲本组合,初步认为新台糖１号×崖８４—１５３、ＣＰ７２／１２１０×崖７１－３７４、ＣＰ７２／１２１０×川５７—４１６和ＣＰ５７—６１４×川５７—４１６为抗锈性强的组合．     

八倍体小偃麦中5的利用

观察比较了八倍体小偃麦中5与利用该材料育成的中梁22号等小麦品种的性状表现.结果表明:中5在株高和生育期方面的缺陷在其后代得到很好的改良;利用中5能够选育出产量性状较好的小麦品种;中5对条锈病和白粉病的抗性遗传能力较强,特别是抗锈性的遗传稳定持久,是难得的抗源材料.同时指出了中5利用中存在植株较高,抗倒伏性差;分离世代较长;生育期长,花期不遇;后代不育,结实性差等问题及其解决的途径.