Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India.
Int J Radiat Biol. 2024;100(7):1072-1084. doi: 10.1080/09553002.2024.2345087. Epub 2024 Apr 29.
Gamma rays are the most widely exploited physical mutagen in plant mutation breeding. They are known to be involved in the development of more than 60% of global cowpea ( (L.) Walp.) mutant varieties. Nevertheless, the nature and type of genome-wide mutations induced by gamma rays have not been studied in cowpea and therefore, the present investigation was undertaken.
Genomic DNAs from three stable gamma rays-induced mutants (large seed size, small seed size and disease resistant mutant) of cowpea cultivar 'CPD103' in M generation along with its progenitor were used for Illumina-based whole-genome resequencing.
Gamma rays induced a relatively higher frequency (88.9%) of single base substitutions (SBSs) with an average transition to transversion ratio (Ti/Tv) of 3.51 in M generation. A > G transitions, including its complementary T > C transitions, predominated the transition mutations, while all four types of transversion mutations were detected with frequencies over 6.5%. Indels (small insertions and deletions) constituted about 11% of the total induced variations, wherein small insertions (6.3%) were relatively more prominent than small deletions (4.8%). Among the indels, single-base indels and, in particular, those involving A/T bases showed a preponderance, albeit indels of up to three bases were detected in low proportions. Distributed across all 11 chromosomes, only a fraction of SBSs (19.45%) and indels (20.2%) potentially altered the encoded amino acids/peptides. The inherent mutation rate induced by gamma rays in cowpea was observed to be in the order of 1.4 × 10 per base pair in M generation.
Gamma-rays with a greater tendency to induce SBSs and, to a lesser extent, indels could be efficiently and effectively exploited in cowpea mutation breeding.
伽马射线是植物诱变育种中应用最广泛的物理诱变剂。据了解，全球超过 60%的豇豆（（L.）Walp.）突变品种都是由伽马射线引起的。然而，伽马射线诱导的豇豆全基因组突变的性质和类型尚未进行研究，因此进行了本研究。
利用 M 代豇豆品种 'CPD103' 的三个稳定的伽马射线诱导突变体（大粒种子、小粒种子和抗病突变体）及其亲本组的基因组 DNA，进行 Illumina 全基因组重测序。
伽马射线在 M 代中诱导了相对较高的频率（88.9%）的单碱基替换（SBS），平均转换颠换比（Ti/Tv）为 3.51。A>G 转换，包括其互补的 T>C 转换，占主导地位的转换突变，而所有四种类型的颠换突变的频率都超过 6.5%。插入缺失（小插入和缺失）约占总诱导变异的 11%，其中小插入（6.3%）比小缺失（4.8%）更为突出。在插入缺失中，单碱基插入缺失，特别是涉及 A/T 碱基的插入缺失占优势，尽管也检测到了比例较低的多达三个碱基的插入缺失。分布在所有 11 条染色体上，只有一小部分 SBS（19.45%）和插入缺失（20.2%）可能改变了编码的氨基酸/肽。在 M 代中，伽马射线诱导的固有突变率观察到为每个碱基对 1.4×10。
伽马射线更倾向于诱导 SBS，在较小程度上诱导插入缺失，可有效地应用于豇豆诱变育种。
