低能N~+离子束诱导小麦农艺性状变异的细胞学基础

用剂量不同的低能(E=30kev)N+离子注入小麦稳定品系CH3286干种子,对M3代植株的株高、生育期(抽穗期)、抗病性、穗型和产量等农艺性状的变异进行了分析,对产生这种诱变效应的细胞学机制进行了细致的研究。结果表明,N+离子注入对小麦农艺性状的影响主要表现在生育期(抽穗期)、株高、穗型和产量性状,对抗病性改善不大。对产量性状的影响主要表现在对千粒重、株粒重、株粒数的影响,使千粒重极显著的降低(F=0.01),而使株粒重和株粒数显著的增加(F=0.05),对穗长、穗颈长、剑叶长、结实小穗数的影响不大。低能N+离子束注入,影响M1代小麦植株花粉母细胞减数分裂,使中期Ⅰ细胞的染色体配对频率降低,单价体频率增高,出现环状染色体、染色体断臂和多价体;在减数分裂后期和末期细胞中,染色体桥、落后染色体、染色体断片和微核等染色体畸变频率比未注入小麦显著增高,其中以染色体断片和微核居多;染色体的畸变频率与离子注入剂量呈正相关,剂量越大,畸变频率越高,变异类型也相对较多。低能N+离子束诱导花粉母细胞减数分裂行为异常是其诱导小麦农艺性状变异的重要原因,并呈明显的剂量效应。

Cytological Mechanism of Trait Variance Induced by Low Energy N+ Ion Beam in Common Wheat

Plant height, ear elongation stage, disease resistance, spike types and yield characters were investigated in M_3 progenies of wheat cultivar CH3286 implanted by low energy N~+ ion beam with different dosages (E=30?kev). Cytological mechanism of trait variance induced by implantation of N~+ ion was analyzed in M_1 progenies. The results show that agronomical trait variances induced by implantation of N~+ ion beam are mainly plant height, ear elongation stage, spike types and yield traits. But disease resistance can not be improved. Grains weight per plant and grain numbers per plant are significantly increased (F=0.05) and TKW significantly decreased (F=0.01) in the N~+ ion treatment. Spike length, spike neck length, flag leaf length, and spikelets per spike are not changed. Meiotic behavior of M_1 progenies is properly abnormal due to implantation of N~+ ion beam. Compared with wheat plants not treated by low energy N~+ ion beam, meiotic pairing frequency is decreased and univalent frequency is increased in metaphase cell. Ring univalent, chromosome arm and multivalent are observed in this duration. More chromosome aberrance types including chromosome fragments and bridges, micronucleus and tagged chromosomes are investigated in anaphase and telophase, in which chromosome fragments and micronucleus are found in the most of PMCs. The degree of meiotic irregularities is positively increased with implanted dosage.