Sequence analysis of the Hsp70 family in moss and evaluation of their functions in abiotic stress responses

Abstract

The 70-kD heat shock proteins (Hsp70s) are highly conserved molecular chaperones that play essential roles in cellular processes including abiotic stress responses. Physcomitrella patens serves as a representative of the first terrestrial plants and can recover from serious dehydration. To assess the possible relationship between P. patens Hsp70s and dehydration tolerance, we analyzed the P. patens genome and found at least 21 genes encoding Hsp70s. Gene structure and motif composition were relatively conserved in each subfamily. The intron-exon structure of PpcpHsp70-2 was different from that of other PpcpHsp70s; this gene exhibits several forms of intron retention, indicating that introns may play important roles in regulating gene expression. We observed expansion of Hsp70s in P. patens, which may reflect adaptations related to development and dehydration tolerance, and results mainly from tandem and segmental duplications. Expression profiles of rice, Arabidopsis and P. patens Hsp70 genes revealed that more than half of the Hsp70 genes were responsive to ABA, salt and drought. The presence of overrepresented cis-elements (DOFCOREZM and GCCCORE) among stress-responsive Hsp70s suggests that they share a common regulatory pathway. Moss plants overexpressing PpcpHsp70-2 showed salt and dehydration tolerance, further supporting a role in adaptation to land. This work highlights directions for future functional analyses of Hsp70s.

The heat‐shock protein/chaperone network and multiple stress resistance

“…Both in mammals and plants, ROS (reactive oxygen species) directly impact HSF oligomerization. ROS are acting as second messengers in a great variety of stresses and H 2 O 2 induces binding of high molecular weight protein complexes on HSEs (Volkov et al, 2006) and trimerization of HSFA1a was shown to occur upon treatment with H 2 O 2 , heat or pH variation . ROS action on transcription factors often depends on the oxidation of one or several Cys residues, but a number of other amino acids could also be potential targets of H 2 O 2 (reviewed in Driedonks et al (2015)).…”

“…The amount of free HSPs is the sensor of the cell capacity to maintain a stable proteome and feeds back on its own production. Indeed, in unstressed tissues, the commonly accepted 'chaperone titration model' specifies that HSFs are sequestered by HSP70/90 and maybe other chaperones (Guo et al, 2001;Volkov et al, 2006). Strong evidences obtained in tomato suggest that an increase in SlHSP70/90 clients leads to liberating HSFs, allowing high HSP and HSF production.…”

“…Indeed, plant land adaptation was shown to be strongly dependent on HSPs as exemplified by the diversification of HSP70. The green algae Chlamydomonas reinhardtii possesses only six HSP70 isoforms, whereas Physcomitrella patens, Oryza sativa and Populus trichocarpa have, respectively, 21, 24 and 20 HSP70 isoforms (Tang et al, 2016). Gene expression analyses revealed moss HSP70 isoforms were responsive to ABA, drought and salt stresses, in addition to heat stress (Tang et al, 2016).…”

“…The green algae Chlamydomonas reinhardtii possesses only six HSP70 isoforms, whereas Physcomitrella patens, Oryza sativa and Populus trichocarpa have, respectively, 21, 24 and 20 HSP70 isoforms (Tang et al, 2016). Gene expression analyses revealed moss HSP70 isoforms were responsive to ABA, drought and salt stresses, in addition to heat stress (Tang et al, 2016). Gene overexpression and knockout studies showed HSP70s from tobacco, soya bean and citrus play a protective role during dehydration stress (Yu et al, 2015).…”

Effects Research of Environmental Hormone BPA and PAEs on the Expression of HSP70-9 Gene in Spinacia oleracea

“…Among these families, HSP70 family is the highly conserved and the most researched gene family [11,15,17,[20][21][22][23][24]. Studies have demonstrated that heat stress [15,[18][19][20][24][25][26][27][28][29][30][31][32], Cold stress [15,24,26,29,30], water stress [22,25,26,33,34], oxidative stresses [19,20,22], heavy metals [9,12,13,35], salt stress [13,19,20,22,34], light stress [27], and chemical contaminants [11,15,18,19,25,[35]…”