Table_1_Volatile profiling as a potential biochemical marker for validation of gamma irradiation derived putative mutants in polyembryonic genotypes of mango (Mangifera indica L.).docx

IntroductionPutative mutants were generated through gamma irradiation in the polyembryonic mango genotype Nekkare. The putative mutant progenies along with control seedlings and mother plants were evaluated by comparing the compositions and relative proportions of their major volatile compounds.MethodsVolatile profiling was done using headspace-solid phase micro-extraction (HS SPME) method coupled with gas chromatography–mass spectrometry (GC-MS MS). Furthermore, characterisation of putative mutants and control seedlings was carried out using simple sequence repeat (SSR) markers to ascertain the genetic diversity present in the samples under study.ResultsMonoterpenes were the most abundant volatile compound in all the studied samples (ranging from 34.76% to 91.41%) out of which I-Phellandrene and cis-Ocimene formed the major fraction in mother plants (20.45%–21.86% and 16.17%–21.27%, respectively) and control seedlings (23.32%–24.95% and 18.95%–20.81%, respectively), while beta-Phellandrene was dominant in the selected putative mutant samples (2.34%–29.53%). Among sesquiterpenes, trans-Caryophyllene was detected only in the putative mutant samples (0.10%–30.18%). Grouping together of mother plants and control seedlings was seen in the cluster analysis, while the putative mutants grouped apart from them suggesting genetic diversity. Genetic distance between the mother plants and control seedlings ranged from 0.97 to 2.73, while between putative mutants, control seedlings, and mother plants, it ranged from 6.54 to 9.82. SSR-based characterisation of putative mutant seedlings showed that mutation caused variability in the treated population. This was evident from the high allelic richness ranging from 4 to 12 with a mean of 7 and a higher mean Shannon’s Information Index (1.50) of the putative mutant population.DiscussionThe study demonstrates that volatile profiling and molecular characterisation using SSR markers could be used as a tool to detect variation in a mutated population. In addition, volatile profiling can be used to validate putative mutants in polyembryonic mango genotypes where the seedlings of nucellar origin are similar to mother plants.

本研究通过对多胚芒果基因型Nekkare进行伽马射线照射产生疑似突变体。对疑似突变体后代、对照种子和母株进行了评估，通过比较其主要挥发性化合物的组成和相对比例。采用顶空固相微萃取（HS-SPME）方法结合气相色谱-质谱-质谱（GC-MS MS）技术进行挥发性分析。此外，利用简单序列重复（SSR）标记对疑似突变体和对照种子进行表征，以确定研究样本中的遗传多样性。结果显示，单萜类化合物在所有研究样本中最为丰富（含量在34.76%至91.41%之间），其中对伞花烃和顺式罗勒烯在母株（含量分别为20.45%至21.86%和16.17%至21.27%）及对照种子（含量分别为23.32%至24.95%和18.95%至20.81%）中占据主要比例，而β-伞花烃则在选定的疑似突变体样本中占主导地位（含量在2.34%至29.53%之间）。在倍半萜类化合物中，仅检测到反式烯丙基香叶烯存在于疑似突变体样本中（含量在0.10%至30.18%之间）。聚类分析显示，母株和对照种子被归为一组，而疑似突变体则与它们分开，表明存在遗传多样性。母株与对照种子之间的遗传距离在0.97至2.73之间，而疑似突变体、对照种子和母株之间的遗传距离在6.54至9.82之间。基于SSR的疑似突变体种子表征表明，突变导致了处理群体中的变异。这从高达4至12的等位基因丰富度以及疑似突变群体较高的平均香农信息指数（1.50）中可见一斑。讨论部分指出，挥发性分析及分子表征（利用SSR标记）可作为检测突变群体中变异的工具。此外，挥发性分析可用于验证多胚芒果基因型中的疑似突变体，其中核源种子与母株相似。