Abstract
Cultivated crops are expected to be less stress tolerant than their wild relatives, leading to efforts to mine wild relatives for traits to increase crop tolerance. However, empirical tests of this expectation often confound tolerance with plant vigor. We assessed whether wild and cultivated Helianthus annuus L. differed for salinity tolerance with 0 and 150 mM NaCl treatments. Salinity tolerance was assessed as the proportional reduction in biomass and as the deviation from expected performance based on vigor. Cultivated accessions had a greater proportional decline in biomass than wild accessions, but proportional decline was positively associated with vigor in both. Thus, wild and cultivated H. annuus did not differ for tolerance when variation in vigor was corrected for statistically. For traits potentially related to tolerance mechanisms, wild and cultivated accessions differed for elemental content and allocation of N, P, K, Mg, Ca, S, Na, Fe, Mn, B, Cu, and Zn for some tissues, biomass allocation, specific leaf area, and leaf succulence. However, these traits were generally unrelated to tolerance corrected for vigor. Osmotic adjustment was associated with tolerance corrected for vigor only in wild accessions where more osmotic adjustment was associated with greater tolerance. Our results for H. annuus suggest that efforts to use wild relatives to enhance crop abiotic stress tolerance will benefit from greater knowledge of traits related to plant growth responses decoupled from vigor, in order to get beyond potential growth-tolerance trade-offs.
Highlights
During plant domestication, humans selectively bred for higher productivity and ease of harvest [1].This has resulted in a host of morphological and physiological changes in crops compared to their wild progenitors, defined by a suite of desirable traits shared by many crops, referred to as the “Domestication Syndrome”, which often includes loss of seed dispersal and dormancy, reduced defensive compounds, and an increase in plant size [2,3,4,5]
Our results for H. annuus suggest that efforts to use wild relatives to enhance crop abiotic stress tolerance will benefit from greater knowledge of traits related to plant growth responses decoupled from vigor, in order to get beyond potential growth-tolerance trade-offs
Salinity stress imposed in this study decreased total biomass in both wild and cultivated H. annuus, but cultivated accessions had a larger proportional decrease than wild accessions (Figure 1A, Table 1, p = 0.001 for interaction between domestication status and salinity treatment)
Summary
Humans selectively bred for higher productivity and ease of harvest [1] This has resulted in a host of morphological and physiological changes in crops compared to their wild progenitors, defined by a suite of desirable traits shared by many crops, referred to as the “Domestication Syndrome”, which often includes loss of seed dispersal and dormancy, reduced defensive compounds, and an increase in plant size [2,3,4,5]. Stress tolerance has often been assessed as relative performance under stressed and non-stressed conditions, where a lower reduction in absolute, percentage or proportional performance indicates higher tolerance [7,8,15,16] This alone neglects differences in plant vigor (defined here as performance under non-stressed conditions), which is generally greater for crop cultivars than their wild progenitors and may influence how plants respond to stress [2,4,17]. Several stress tolerance indices exist that weight the stress-induced reduction in growth by vigor in some manner, in order
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
