Transcriptome Analysis of Pyrus betulaefolia Seedling Root Responses to Short-Term Potassium Deficiency

Abstract

Potassium (K) plays a crucial role in multiple physiological and developmental processes in plants. Its deficiency is a common abiotic stress that inhibits plant growth and reduces crop productivity. A better understanding of the mechanisms involved in plant responses to low K could help to improve the efficiency of K use in plants. However, such responses remain poorly characterized in fruit tree species such as pears (Pyrus sp). We analyzed the physiological and transcriptome responses of a commonly used pear rootstock, Pyrus betulaefolia, to K-deficiency stress (0 mM). Potassium deprivation resulted in apparent changes in root morphology, with short-term low-K stress resulting in rapidly enhanced root growth. Transcriptome analyses indicated that the root transcriptome was coordinately altered within 6 h after K deprivation, a process that continued until 15 d after treatment. Potassium deprivation resulted in the enhanced expression (up to 5-fold) of a putative high-affinity K+ transporter, PbHAK5 (Pbr037826.1), suggesting the up-regulation of mechanisms associated with K+ acquisition. The enhanced root growth in response to K-deficiency stress was associated with a rapid and sustained decrease in the expression of a transcription factor, PbMYB44 (Pbr015309.1), potentially involved in mediating auxin responses, and the increased expression of multiple genes associated with regulating root growth. The concentrations of several phytohormones including indoleacetic acid (IAA), ABA, ETH, gibberellin (GA3), and jasmonic acid (JA) were higher in response to K deprivation. Furthermore, genes coding for enzymes associated with carbon metabolism such as SORBITOL DEHYDROGENASE (SDH) and SUCROSE SYNTHASE (SUS) displayed greatly enhanced expression in the roots under K deprivation, presumably indicating enhanced metabolism to meet the increased energy demands for growth and K+ acquisition. Together, these data suggest that K deprivation in P. betulaefolia results in the rapid re-programming of the transcriptome to enhance root growth and K+ acquisition. These data provide key insights into the molecular basis for understanding low-K-tolerance mechanisms in pears and in other related fruit trees and identifying potential candidates that warrant further analyses.

Mechanical properties of stem and physiological–biochemical responses of cucumber under different N and K conditions

“…N affected crop growth externally by reducing leaf area and green leaf lifespan, and internally by inhibiting the synthesis of chlorophyll and protein to reduce photosynthetic products (Dos Santos et al, 2020;Mu and Chen, 2021). K + participated in protein synthesis, photosynthesis, enzyme activation, regulation of osmosis, and ion homeostasis (Li et al, 2021c), and the research of Yang, H. et al showed that under low K + condition, the K + concentration of old leaves decreased, but the concentration of new leaves changes little because of the highly mobile potassium in the crop (Yang et al, 2020). In addition, phloem transportation and biomass partitioning also depended on the regulation of K + (Li et al, 2021d).…”

Transcriptome Analysis Unravels Key Factors Involved in Response to Potassium Deficiency and Feedback Regulation of K+ Uptake in Cotton Roots

“…Also, only three GhHAK5 genes and one GhKUP3 gene were induced by low K + in the roots of both grafts in this study ( Figure 6 a). The transcripts of members of the KUP/HAK/KT family usually increased under K + deficiency [ 34 , 36 , 37 ]. Moreover, genotypic differences in K + efficiency were associated with the number and amplitude of up-regulated K + transporter genes in cotton [ 41 ] and wheat [ 67 ].…”

“…The expression of Nitrate transporter 1/peptide transporter ( NRT1/PTR ) genes regulated by external potassium has been reported for Arabidopsis [ 31 ], rice [ 34 ], wheat [ 67 ], banana [ 47 ], and pear [ 37 ]. Consistently, we identified several up-regulated GhNRT2.1s in the roots of SCRC22/CCRI41 ( Figure 6 a, b).…”

“…A wide array of transcriptome studies found dozens to hundreds of differently expressed TFs in response to K + deficiency in plants, and MYB, ERF and WRKY families were most commonly identified [ 37 , 47 , 59 , 65 , 84 ], suggesting their implications in coping with external K + deprivation. In this study, we identified 67 and 201 DEGs encoding TFs in the roots of both grafts and only in the roots of SSCRC22/CCRI41 under K + deficiency ( Supplementary Figure S5 ).…”

“…Previous reports showed that the genes encoding K + transporters, especially members of the KUP/HAK/KT family were mostly identified in response to K + deficiency or deprivation [ 34 , 35 , 36 , 37 ]. The HAK5 genes under K + deprivation were strongly induced in roots of Arabidopsis ( AtHAK5 ) [ 38 ], pepper ( CaHAK5 ) [ 39 ], tomato ( LeHAK5 ) [ 40 ], and cotton ( GhHAK5 ) [ 41 ].…”