The tolerance of tree growth to drought in diverse mixed forests subjected to seasonal water shortage is understudied despite their ecological and economic relevance.By combining intra-and inter-annual analyses of rad...The tolerance of tree growth to drought in diverse mixed forests subjected to seasonal water shortage is understudied despite their ecological and economic relevance.By combining intra-and inter-annual analyses of radial growth responses to climate and drought at daily and monthly scales,different strategies to acclimate to hydroclimate variability of coexisting conifers and broadleaves were unveiled.We analyzed the growth patterns and responses to hydroclimate variability in two conifers(Pinus engelmannii,Juniperus deppeana)and two broadleaves(Quercus grisea,Arbutus arizonica)co-occurring in a Madrean pine-oak forest located in NW Mexico.The strongest positive response to daily precipitation was found in the two conifers,but this response peaked earlier in J.deppeana than in P.engelmannii,which presented a more delayed formation of radially-enlarging tracheids.The latest negative response to temperature was found in Q.grisea,which agrees with its more delayed xylogenesis than A.arizonica.P.engelmannii presented the highest responsiveness to water shortage,driven by lower precipitation and high maximum temperatures,responding to longer droughts ending in autumn(r=0.72),whilst A.arizonica showed the lowest responsiveness to short spring droughts(r=0.39).Growth of P.engelmannii was linked to climate-atmospheric circulation patterns over the near Pacific Ocean.Overall,P.engelmannii and A.arizonica showed high growth rates and earlier growth onset,whilst J.deppeana and Q.grisea showed slower growth rates and later growth onset.The Vaganov-Shashkin growth model evidenced that winterspring soil moisture was the key driver of growth.Under more arid conditions and more frequent and hotter droughts,pine stands could rapidly shift towards mixed pine-oak forests.展开更多
In temperate regions, latewood is produced when cambial activity declines with the approach of autumnal dormancy. The understanding of the temporal （cambium activity vs dormancy） and spatial （phloem, cambial region...In temperate regions, latewood is produced when cambial activity declines with the approach of autumnal dormancy. The understanding of the temporal （cambium activity vs dormancy） and spatial （phloem, cambial region, maturing xylem） regulation of key genes involved in the phenylpropanoid pathway during latewood formation represents a crucial step towards providing new insights into the molecular basis of xylogenesis. In this study, the temporal pattern of transcript accumulation of 12 phenylpropanoid genes （PAL1, C4H315, C4H4, 4CL3, 4CL4, HCT1, C3H3, CCoAOMT1, COMT2, COMT5, CCR2） was analyzed in maturing xylem and phloem of Picea abies during latewood formation. Quantitative reverse transcription-polymerase chain reaction analyses revealed a well-defined RNA accumulation pattern of genes involved in the phenylpropanoid pathway during latewood formation. Differences in the RNA accumulation patterns were detected between the different tissue types analyzed. The results obtained here demonstrated that the molecular processes involved in monolignol biosynthesis are not restricted to the cambial activity timeframe but continued after the end of cambium cell proliferation. Furthermore, since it has been shown that lignification of maturing xylem takes place in late autumn, we argue on the basis of our data that phloem could play a key role in the monoliqnol biosynthesis process.展开更多
基金funding by the Science and Innovation Ministry(projects PID2021-123675OB-C43 and TED2021-129770B-C21).
文摘The tolerance of tree growth to drought in diverse mixed forests subjected to seasonal water shortage is understudied despite their ecological and economic relevance.By combining intra-and inter-annual analyses of radial growth responses to climate and drought at daily and monthly scales,different strategies to acclimate to hydroclimate variability of coexisting conifers and broadleaves were unveiled.We analyzed the growth patterns and responses to hydroclimate variability in two conifers(Pinus engelmannii,Juniperus deppeana)and two broadleaves(Quercus grisea,Arbutus arizonica)co-occurring in a Madrean pine-oak forest located in NW Mexico.The strongest positive response to daily precipitation was found in the two conifers,but this response peaked earlier in J.deppeana than in P.engelmannii,which presented a more delayed formation of radially-enlarging tracheids.The latest negative response to temperature was found in Q.grisea,which agrees with its more delayed xylogenesis than A.arizonica.P.engelmannii presented the highest responsiveness to water shortage,driven by lower precipitation and high maximum temperatures,responding to longer droughts ending in autumn(r=0.72),whilst A.arizonica showed the lowest responsiveness to short spring droughts(r=0.39).Growth of P.engelmannii was linked to climate-atmospheric circulation patterns over the near Pacific Ocean.Overall,P.engelmannii and A.arizonica showed high growth rates and earlier growth onset,whilst J.deppeana and Q.grisea showed slower growth rates and later growth onset.The Vaganov-Shashkin growth model evidenced that winterspring soil moisture was the key driver of growth.Under more arid conditions and more frequent and hotter droughts,pine stands could rapidly shift towards mixed pine-oak forests.
基金supported by the project SOFIE-2(Reg.Delib.No.3012-2007)funded by the Provincia Autonoma di Trento,Italy
文摘In temperate regions, latewood is produced when cambial activity declines with the approach of autumnal dormancy. The understanding of the temporal （cambium activity vs dormancy） and spatial （phloem, cambial region, maturing xylem） regulation of key genes involved in the phenylpropanoid pathway during latewood formation represents a crucial step towards providing new insights into the molecular basis of xylogenesis. In this study, the temporal pattern of transcript accumulation of 12 phenylpropanoid genes （PAL1, C4H315, C4H4, 4CL3, 4CL4, HCT1, C3H3, CCoAOMT1, COMT2, COMT5, CCR2） was analyzed in maturing xylem and phloem of Picea abies during latewood formation. Quantitative reverse transcription-polymerase chain reaction analyses revealed a well-defined RNA accumulation pattern of genes involved in the phenylpropanoid pathway during latewood formation. Differences in the RNA accumulation patterns were detected between the different tissue types analyzed. The results obtained here demonstrated that the molecular processes involved in monolignol biosynthesis are not restricted to the cambial activity timeframe but continued after the end of cambium cell proliferation. Furthermore, since it has been shown that lignification of maturing xylem takes place in late autumn, we argue on the basis of our data that phloem could play a key role in the monoliqnol biosynthesis process.
