Isolation and characterization of gamma rays induced mutants for improved agro-morphological performance and harder grain texture in wheat (Triticum aestivum L.)

Kernel texture plays a principal role in determining technological flour properties and end-use quality of wheat products. Hence, a multi-year mutation induction programme was conducted to isolate advanced wheat mutant lines with agro-morphologically superior performance, higher disease resistance and harder grain texture. Radiation mutagenesis was employed in soft textured wheat variety HPW 89 using gamma rays dose of 250, 300 and 350 Gy (Co60: BARC, Mumbai) and evaluated across M1–5 generations. Promising superior mutants selected were evaluated during M4 and M5 generation for induced variability and trait association for agro-morphological and quality traits. The screened mutants were also determined for induced changes at genetic level using gene specific markers for puroindoline genes. A total of 293 agro-morphologically superior mutants isolated showed significant genetic variation in the M4 generation. Single kernel characterization system categorized 267 mutants (8.79–50.06) with higher grain hardness than the HPW 89 variety (7.39). Among these, 108 mutants were selected for agro-morphological and molecular characterization. Significant variations were found in these mutants in either pina and pinb or both puroindoline genes. Clustering among these mutants led to the formation of five clusters and a total of eleven mutants were found with better set of agro-morphological, disease resistance and quality traits. These mutants can serve as important genetic resource for developing harder texture bread wheat varieties in the future grain quality improvement programmes. These mutants will also bridge the need of bakers and millers’ requirement of varieties with specific texture and quality.

籽粒质地（Kernel texture）是决定小麦面粉加工特性与终端产品品质的核心影响因素。为此，本研究开展了多年诱变育种项目，旨在筛选兼具优良农艺性状、更高抗病性与更硬籽粒质地的优异小麦突变株系。
本研究以软质小麦品种HPW 89为供试材料，采用孟买巴巴原子研究中心（BARC）的钴-60（Co⁶⁰）源产生的γ射线进行辐照诱变，设置250、300、350 Gy三个剂量梯度，并在M₁至M₅代开展多代选育评价。
针对筛选获得的优良突变体，在M₄与M₅代开展诱导变异分析及农艺、品质性状间的关联研究；同时利用puroindoline基因（Puroindoline genes）特异性分子标记，对筛选突变体的遗传水平变异进行检测。
在M₄代中共筛选得到293份农艺性状优异的突变体，均表现出显著的遗传变异。采用单籽粒测定系统（Single Kernel Characterization System）进行籽粒硬度检测，结果显示267份突变体的籽粒硬度值介于8.79~50.06之间，显著高于亲本HPW 89的硬度值（7.39）。
从中选取108份突变体开展农艺性状与分子特征鉴定。检测发现，这些突变体在pina、pinb基因或二者兼具的puroindoline基因位点上均存在显著变异。
对该批突变体进行聚类分析，将其划分为5个类群，其中11份突变体同时具备优异的农艺性状、抗病性与品质性状。
该批突变体可作为未来硬质面包小麦品种籽粒品质改良的重要遗传资源。
同时可满足烘焙与面粉加工产业对特定质地及品质小麦品种的产业需求。